And Then There Were None — Agatha Christie (1939)

And Then There Were None is the best-selling mystery novel of all time, with over 100 million copies sold. Its plot traps ten strangers on an island where they die one by one, following a nursery rhyme—a locked-room puzzle so airtight it still astonishes readers 85 years later. This intricate construction outperforms #3 Gone Girl in sheer structural genius, and its solution remains more surprising than the average modern thriller.